Process of extracting precious metals.



* NITED STATES PATENT OFFICE.

CHARLES P. TATRO AND GEORGE DELIUS, OF SEATTLE, WASHINGTON.

PROCESS OF EXTRACTING PRECIOUS METALS.

SPECIFICATION formingpart of Letters Patent No. 653,325, dated July 10, 1900.

Application filed October 4, 1899. Serial No. 732,548. (No specimens.)

To all whom it may concern:

Be it known that we, CHARLES P. TATRO and GEORGE DELIUS, citizens of the United States, residing at Seattle, in the county of King and State of Washington, have invented a new and useful Improvement in Processes for Extracting Precious Metals; and we do hereby declare the following to be a full, clear, and exact description of the same.

Our invention relates to means for separating precious metals from ores by the action of electrolysis; and its object is to liberate from certain refractory ores a larger percentage of the precious metals contained in them than has heretofore been done, so that the said metals may be recovered by means of electrolytic action.

To this end our invention consists in certain steps in the process of electrolytically separating precious metals from ores, hereinafter more fully described, and particularly pointed out in the claims.

In conducting this process we first pulverize the ore to a pulp suitably fine, the degree of fineness being controlled in practice by the useof a screen of about eighty mesh, the pulp that passes through the mesh being fine enough to work well. The second step is to immerse the pulp in a bath comprising common salt, caustic lime, fiuor-spar, saltpeter, and a small percentage of bromin. The third step is to recover the precious metals which are held in suspension or. solution in the bath by means of electrolytic action. The reduction of the ore to a pulp, the necessary agitation of the bath during the process of separation, and the electrolytic recovery of the precious metals from the bath may be effected in any usual or preferred manner, the novelty of our process consisting mainly in the second step above named.

Heretofore we have found that caustic lime would economically precipitatethe iron which is common in most ores, but is undesirable in the electrolyte. We have sometimes found it necessary to use acid to dissolve undesirable metals and then precipitate them by means of a suitable alkali. We use a salt solution stronger than is necessary to do the work, as the work only consumes a certain small percentage from the solution. To a ten-per-cent.-salt solution add ten pounds fiuor-spar, one pound of saltpeter, and five ounces of bromin to each ton of ore. This is an average, but only applies to that class of ores which require the entire combination. The greater majority of ores only require salt, saltpeter, and a small quantity-say one poundof sulfuric acid to a ton of ore.

The composition of our bath is designed to meet the general requirement of dissolving gold and silver from the various ores usually met with; but its peculiarity in this case adapts it for use in working the'most refractory ores-such as the telurides of iron, copper,and antin1ony-and we findthat the addition of the fiuor-spar and saltpeter enables us to work ores containing a large percentage of silicon, as well as zinc-blende, arsenic, and sulfur, up to a high degree of extraction in a short time and at little or no extra cost, because the fluor-spar and saltpeter are inexpensive, and we use them in'very small proportionate quantities.

The large percentage of precious metals obtained from refractory ores by this process and the insignificant additional expense of the peculiar ingredients used render this process economical and profitable.

Having thus fully described ourinvention, what we believe to be new, and desire to secure by Letters Patent, is the following:

1. In extracting precious metals from ores, the process comprising the following steps; first, pulverizing the ore to a fine pulp; second, dissolving the metals from the foreign matter by immersing the pulp in a bath comprising an aqueous solution of common salt, caustic lime, and a small percentage of bromin fluor-spar and saltpeter; third, recovering the precious metals from the bath by means of electrolytic action.

2. In the process of extracting precious metals from ores, the steps comprising the reduction of the ore to a pulp; dissolving the precious metals from the ore in the pulp in a bath comprising fluor-spar, saltpeter and solvents for the precious metals; and recovering the precious metals from the bath by means of electrolytic action.

In testimony whereof we aflix our signatures in presence of two witnesses.

CHARLES P. TATRO. GEORGE DELIUS.

Witnesses:

L. B. STEDMAN, F. SAWYER. 

